A metaphor is a figure of speech that says that one thing is another different thing. This allows us to use fewer words and forces the reader or listener to find the similarities, for example:- Her home was a prison.- George is a pig.

A simile is a figure of speech that says that one thing is like another different thing. We can use similes to make descriptions more emphatic or vivid. We often use the words "as...as" and "like" with similes. But we can also use words such as "than" and "as if", for example:- His skin was as cold as ice.- George eats like a pig.- He is larger than life.- They ran as if for their lives.

It follows therefore that "the meal looked as if it had been put together by a chimp" is a simile. Perhaps someone can rephrase it as a metaphor?

For full details and examples please see EnglishClub's pages on:- similes- metaphors